On many communication buses there is a single bus controller computer or bus control unit that is the only computer allowed to transmit and request messages from other remote terminals on the bus. By way of example and not by way of limitation, such a configuration is provided in a MIL-STD-1553 bus, such as used in certain aircraft avionics systems where a MIL-STD-1553 avionics bus is the means of communications among navigation equipment, display equipment, communications equipment and other devices.
There may be occasions where one needs to provide or coordinate information from other devices with the avionics system, but it may be desirable to avoid the complexity and expense that may be involved in providing for coordination between the first bus control unit and a second bus control unit.
There is a need for a method and apparatus for employing a second bus controller on a data bus having a first bus controller to allow a second bus controller on a data bus without requiring any direct coordination with the existing first bus controller.
There is a need for a method and apparatus for employing a second bus controller on a data bus having a first bus controller that may enable a second bus controller to observe the actions of a first bus controller, and use these observations to determine when it is safe to act on the bus without interfering with operation of the first bus controller.